linux-kernel - Re: [PATCH v3 RESEND] x86/asm/entry/32, selftests: Add test_syscall

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Date:	Mon, 6 Jul 2015 14:44:55 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Oleg Nesterov <oleg@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Will Drewry <wad@...omium.org>,
	Kees Cook <keescook@...omium.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH v3 RESEND] x86/asm/entry/32, selftests: Add
 test_syscall_vdso test


* Denys Vlasenko <dvlasenk@...hat.com> wrote:

> The test checks that all registers are preserved across
> 32-bit syscalls. It tests syscalls through VDSO
> (if available) and through INT 0x80, normally
> and under ptrace.
> 
> If kernel is a 64-bit one, high registers (r8..r15) are poisoned
> before call and checked afterwards. They must be either preserved,
> or cleared to zero (but r11 is special); r12..15 must be preserved
> for INT 0x80.
> 
> EFLAGS is checked for changes too, but change there is not considered
> to be a bug (paravirt kernels do not preserve arithmetic flags).
> 
> Run-tested on 64-bit kernel:
> 
> $ ./test_syscall_vdso_32
> [RUN]	Executing 6-argument 32-bit syscall via VDSO
> [OK]	Arguments are preserved across syscall
> [NOTE]	R11 has changed:0000000000200ed7 - assuming clobbered by SYSRET insn
> [OK]	R8..R15 did not leak kernel data
> [RUN]	Executing 6-argument 32-bit syscall via INT 80
> [OK]	Arguments are preserved across syscall
> [OK]	R8..R15 did not leak kernel data
> [RUN]	Running tests under ptrace
> [RUN]	Executing 6-argument 32-bit syscall via VDSO
> [OK]	Arguments are preserved across syscall
> [OK]	R8..R15 did not leak kernel data
> [RUN]	Executing 6-argument 32-bit syscall via INT 80
> [OK]	Arguments are preserved across syscall
> [OK]	R8..R15 did not leak kernel data
> 
> On 32-bit paravirt kernel:
> 
> $ ./test_syscall_vdso_32
> [NOTE]	Not a 64-bit kernel, won't test R8..R15 leaks
> [RUN]	Executing 6-argument 32-bit syscall via VDSO
> [WARN]	Flags before=0000000000200ed7 id 0 00 o d i s z 0 a 0 p 1 c
> [WARN]	Flags  after=0000000000200246 id 0 00 i z 0 0 p 1
> [WARN]	Flags change=0000000000000c91 0 00 o d s 0 a 0 0 c
> [OK]	Arguments are preserved across syscall
> [RUN]	Executing 6-argument 32-bit syscall via INT 80
> [OK]	Arguments are preserved across syscall
> [RUN]	Running tests under ptrace
> [RUN]	Executing 6-argument 32-bit syscall via VDSO
> [OK]	Arguments are preserved across syscall
> [RUN]	Executing 6-argument 32-bit syscall via INT 80
> [OK]	Arguments are preserved across syscall
> 
> Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
> CC: Linus Torvalds <torvalds@...ux-foundation.org>
> CC: Steven Rostedt <rostedt@...dmis.org>
> CC: Ingo Molnar <mingo@...nel.org>
> CC: Borislav Petkov <bp@...en8.de>
> CC: "H. Peter Anvin" <hpa@...or.com>
> CC: Andy Lutomirski <luto@...capital.net>
> CC: Oleg Nesterov <oleg@...hat.com>
> CC: Frederic Weisbecker <fweisbec@...il.com>
> CC: Alexei Starovoitov <ast@...mgrid.com>
> CC: Will Drewry <wad@...omium.org>
> CC: Kees Cook <keescook@...omium.org>
> CC: x86@...nel.org
> CC: linux-kernel@...r.kernel.org
> ---
> 
> Changes in v2:
>  does not fail if VDSO can't be found;
>  tests INT 80 syscall method;
>  tests syscalls under ptrace;
>  switched to /* */ comments
> 
> Changes in v3:
>  added checking for r8..r15 info leaks
> 
>  tools/testing/selftests/x86/test_syscall_vdso.c | 401 ++++++++++++++++++++++++
>  tools/testing/selftests/x86/thunks_32.S         |  55 ++++
>  2 files changed, 456 insertions(+)
>  create mode 100644 tools/testing/selftests/x86/test_syscall_vdso.c
>  create mode 100644 tools/testing/selftests/x86/thunks_32.S

Hm, what I don't see is any Makefile integration. How am I supposed to build this 
test, and how will automated tests pick this testcase up?

Thanks,

	Ingo
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